Ectopic opening of common bile duct into the duodenal bulb: magnetic resonance cholangiopancreatography findings.

PURPOSE We aimed to evaluate the spectrum of magnetic resonance cholangiopancreatography (MRCP) findings in patients with ectopic opening of the common bile duct (CBD) into the duodenal bulb and to determine the effectiveness of the MRCP technique in diagnosis. METHODS Morphologic and morphometric MRCP/MRI features in 16 patients and 36 controls were retrospectively analyzed by 2 radiologists. The frequency of MRCP findings was determined. The significance of the difference between the MRCP observations in patients and controls was evaluated statistically and the diagnostic effectiveness of MRCP was investigated. RESULTS Hook-shaped ending of CBD and bulbar deformity were the most frequent morphologic findings seen on MRCP in the ectopic bulbar opening. Mean pylorus-papilla distance and mean CBD length were significantly shorter and the median diameter of CBD was significantly larger than the control group (patients: 28.6 ± 15.3 mm, 33.7 ± 12.8 mm, 8.6 (2-16) mm; controls: 66.7 ± 11.7 mm, 50.3 ± 14.4 mm, 3.2 (1.5-10) mm, P < .001, respectively). Receiver operating curve analysis showed sensitivity and specificity of MRCP in the diagnosis to be 87.5% and 100%, respectively, if any 3 of the 4 signs (hook-shaped ending of CBD, bulbar deformity, large, and short CBD) were present in a patient whose pylorus-papilla distance was <50 mm. CONCLUSION At MRCP, the presence of short and large CBD with a hook-shaped ending in the deformed duodenal bulb may support the diagnosis of ectopic biliary drainage.